Circuit breaker interlock



Filed Feb. 17, 193B 2 sheets-sheet 1 OCt- 24, 1939- T. w. LANGFORDCIRCUIT BREAKER NTERLOCK INVENTOR /was/fy//o/z ATTORN Y WITNESSES:

Oct. 24, 1939. T. w. LANGFORD CIRCUIT BREAKER INTERLOCK Filed Feb. 17,1938 2 Sheets-Sheet 2 WITNESSES:

Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE CIRCUIT BREAKERINTERLOCK of Pennsylvania Application February 17, 1938, Serial No.191,011

6 Claims.

The invention relates to enclosed circuit breakers in general, and moreparticularly to a safety interlocking means for the cover of the circuitbreaker casing.

An object of the invention is the provision of an enclosed circuitbreaker having a casing and an openable cover therefor with an improvedinterlocking means for interlocking the cover and the circuit breakermechanism so that the cover cannot be opened when the circuit breaker isin closed circuit position.

Another object of the invention is the provision of an enclosed circuitbreaker having an overcenter snap acting operating mechanism and amanual operating member therefor with an improved interlocking meansbetween the cover and operating member for preventing opening of thecover when the breaker is closed, the interlocking means being effectiveduring the full travel 'of the operating member from closed circuitposition to the point at which the mechanism automatically actuates thecontacts to open position independently of any further movement of theoperating member, so that the interlocking means cannot be released bymoving the operating member only part of the way to open position.

Another object of the invention is the provision of an enclosed circuitbreaker with an improved interlocking means for preventing opening oftheenclosure cover when the breaker is in closed circuit position, theinterlocking means being disposed in a-n inaccessible position entirelywithin the enclosure so that it cannot be released from Outside theenclosure except by moving the reaker operating member to open circuitposilon.

Another object of the invention is the provision of an enclosed circuitbreaker with an im,- proved interlocking means between the enclosurecover and operating mechanism of the breaker for preventing opening ofthe cover when the breaker is in closed circuit position, and whichpermits closing of the cover when the breaker is in closed position.

Another object of the invention is the provision of a safetyinterlocking means as described above that is simple, reliable inoperation and inexpensive to manufacture.

The novel features that are considered characteristic of the inventionare set forth in particular in the appended claims. The inventionitself, however, both as to structure and operation, together withadditional objects and advantages thereof will be best understood fromthe following detailed description of a preferredembodi- (Cl. ZOO-50)ment thereof when read in connection with the accompanying drawings inwhich:

Figure l is a plan view of a circuit breaker embodying the safetyinterlocking means of the present invention, a portion of the cover ofthe circuit breaker enclosure being broken away.

Fig. 2 is a side elevational view partly in section, of the circuitbreaker shown in Fig. l, and

Fig, 3 is an end elevational view of the circuit breaker with a portionof the cover and casing broken away to illustrate the safetyinterlocking means.

The interlocking means of the present invention is shown in theaccompanying drawings applied to a circuit breaker which issubstantially identical in construction and operation to the circuitbreaker disclosed in the copending application of L. Pierce and S.Miller, Serial No. 187,446, led January 28, 1938, and assigned to theassignee of the present invention. Since the structural details andoperation of the circuit breaker have been completely shown anddescribed in the above-mentioned copending application, only so muchthereof is shown and described in this application as is considerednecessary for a complete understanding of the present invention.

Referring to the drawings, the numeral designates a sheet metalenclosure formed by a substantially rectangular casing 'I and acooperating cover 9 which is pivotally mounted on the casing 'I by ahinge means Il. The cover is releasably held in closed position on thecasing by means of a pivoted spring biased latchI I3 mounted on thecover 9, which engages the edge of an opening provided in an end wall ofthe casing 1.

A multipole circuit breaker unit 4carried by a base I5 is mounted Withinthe enclosure 5, The circuit breaker unit comprises in general aplurality of pairs of spaced stationary contacts I1, a plurality ofcooperating movable bridging contact members I9 for forming a pluralityof poles, and an operating mechanism indicated generally at 2l foroperating the movable bridging contact members I9.

The movable bridging contact members I9 are mounted in tranverse spacedrelation on a cross arm 23 of insulating material which is securedintermediate its ends to the outer end of a switch member 25. The switchmember 25 is mounted for linear rolling movement on a U-shaped frame 2lby means of a roller 29 which extends transversely between the sidewalls of the frame 2l'.

The operating mechanism 2l is carried by the frame 21 between the sideWalls thereof and includes a releasable carrier Eil pivoted at 53 in theframe 21. A pair of actuating links are piv oted at their upper ends bymeans of a pivot pin 31 on the carrier 3| and have their lower endspivotally connected by means of a pivot pin 39 to the inner end of themovable switch member R5. A U-shaped operating member 4i pivotallymounted on a pair of lugs 43 struck outwardiy from the side walls of theframe and is connected to the inner end of the movable switch member 25by a pair of overcenter springs 45, which have their upper endsconnected te the bight portion of the operating member 4l and theirlower ends connected to the pivot pin which connects the actuating links35 to the switch member 25. The upper end oi the operating member 4| hasan insulating operating handle 41 secured thereto which projects t.rough an elongated opening 49 provided in well 5l formed in the cover 9.The operating member 4| is also provided with an arcuate shield whichserves to close the opening 49 in all positions of the operating member,and with a depending projection 55 which serves to reset the mechanismfollowing a tripping operation.

The releasable carrier 3| is biased in a clockwise direction about itspivot axis 33 bythe overcenter springs 45 and is releasably held in anormal latched position by a main latch member 51 which is pivoted onthe frame 2'! by a pivot pin 59, the carrier 3| being provided with arounded latch nose El which normally engages the upper edge of anopening t3 provided in the .main latch 51. The main latch 51 is in turnreleasably held in its latched position, against the releasing forcetransmitted thereto by the overcenter springs 45, by means of a secondlatch 65 which is pivoted on the main frame 21 by means of a pin B1. Thesecond latch G5 is biased in a clockwise direction by a helical spring69 interposed between the latch 65 and the base of the frame 21, and thelatch B5 is held against movement beyond the latching position as shownin Fig. 2 by an inwardly bent projection 1i formed in the end of themain latch 51.

A pair of current responsive release units indicated generally at 13(Fig. l) are detachably mounted on opposite sides of the main frame 21and each includes a snap acting bimetal disk and a heater coil (notshown) which are mounted within an insulating block 15. The heater coilsof the two current responsive release units 13 are connected in seriescircuit with the contact means of the two outer poles of the breaker bya pair of iiexible shunt conductors 11 so as to be heated in response tothe current flowing in the outer poles of the breaker. The bimetal diskof each current responsive release device 13, when heated apredetermined amount in response to an overload in the circuit of itspole, moves with a snap action from its original position to an invertedposition and acts through an insulating button 19 and a trip lever 8|which extend through the side wall of the frame 21 to effect downward orcounterclockwise movement of the second latch 65 to trip the circuitbreaker to open position. When the bimetal disc is cooled below apredetermined temperature following a tripping operation it returns toits original position.

The operation of the circuit breaker as thus far described is briefly asfollows:

To manually open the circuit breaker the op erating member 4| is movedby the handle 4'.' in a counterclockwise direction about its pivot axis43 from the closed position shown in Fig. 2 to the open positionadjacent the opposite end of the elongated opening 49. This movement ofthe operating member 4| moves the line of action of the overcentersprings 45 towards the left as viewed in Fig. 2. When the operatingmember reaches the position indicated by the dotted lines in Fig. 2, theline of action of the overcenter springs 45 has been carried across theaxis of the pivot pin 31 which connects the upper ends of the actuatinglinks 35 to the carrier 3|, and the force exerted by the overcentersprings moves the switch member 23 and the movable bridging contacts I9carried thereby to open circuit position with a snap actionindependently of any further movement of the operating mem ber 4|. Theforce exerted by the overcenter springs also acts to carry the operatingmember 4| onto its full open circuit position.

To close the circuit breaker the operating member 4| is moved by thehandle 41 in a clockwise direction about its pivot axis 43 from the opencircuit position to the closed circuit position shown in Fig. 2. At acertain point in the closing movement of the operating member, the lineof action of the overcenter springs 45 moves to the right of the pivotpin 31 following which the force exerted by the springs moves the switchmember 25 and the bridging contact members I9 carried thereby to closedposition with a snap action. The operating member 4| is also moved ontothe full closed circuit position by the force exerted by the overcentersprings. It will thus seen that no matter how slowly the operatingmember is moved to operate the circuit breaker, the switch member 25 andmovabe contacts are aways moved with a snap action after the operatingmember has been moved a predetermined amount in either direction.

If an overload of predetermined magnitude and duration occurs in thecircuits of either of the outer poles of the breaker the bimetal disk ofthe current responsive release unit 13 of the afe fected pole moves toits inverted position to eflect release of the latches 51 and 65, andthe carrier 3|. When the carrier is thus released in response to anoverload, it is moved in a clockwise direction about its pivot axis bythe overcenter springs 45. The clockwise movement of the carrier 3|,following its release, carries the pivot pin 31 to the right of the lineof action of the overcenter springs 45, and the overcenter springs thenmove the switch member 25 to a tripped open circuit position and theoperating member 4| and handle 41 to an intermediate tripped indicatingposition.

Before the circuit breaker can be reclosed following a trippingoperation as described above, it is necessary to reset the carrier 3|and the latches 51 and 65. To reset the mechanism, the operating member4| is moved in a counterclockwise direction about its pivot axis 43toward open position. During this resetting movement of the operatingmember, the depending projection 55 thereof engages and moves thecarrier 3| in a counterclockwise direction. The carrier 3| is moved in acounterclockwise direction slightly beyond the latched position shown inFig. 2 to effect resetting of the main latch 51 and the second latch B5.When the carrier 3| returns to its latched position after latches 51 and65 have been reset, the latch nose 5| thereof is reengaged under theedge of the opening B3 in the main latch member 51. The mechanism is nowcompletely reset and the circuit breaker may be reclosed in the mannerpreviously described.

A novel safety means is provided for interlocking the cover 9 of theenclosure 5 to prevent opening thereof whenever the circuit breaker isin its closed circuit position. The interlocking means comprises alateral projection 83 formed integral with the operating member 4| bybeing struck out from the upper end of one of the legs of the operatingmember, and a cooperating springclop which is secured to the inside ofthe cover 9, .either by welding or by mechanical means, and positionedat the side of the well 5| and elongated opening 49 thereof. The lowerend of the clip 85 is angularly bent back as shown in Fig. 3 to providea hooked end 81 (Fig. 3), and the clip 85 is so disposed that the hookedend lies in interlocking relation under the lateral projection 83 of theoperating member 4| when the operating member 4| is in and adjacent toits closed circuit position -as shown in Fig. 2, thus preventing openingof the cover 9 when the circuit breaker is in closed circuit position.

As will be seen in Fig. 1, the clip 85 is of a Width such that the lefthand edge thereof is disposed directly above the axis of the pivot pin31 which supports the actuating links 35, thus rendering theinterlocking means eiTective to interlock the cover 9 during the fulltravel of the operating member 4| from closed position to the positionat which the operating mechanism 2| continues` its movementautomatically to open the circuit breaker independently of any furtheropening movement of the operating member 4|. The last mentioned criticalintermediate position of the operating member 4| is indicated by thedotted lines in Fig. 2 and it Will be noted that in this position thelateral projection 83 of the operating member 4| has just cleared thehook end 81 of the spring clip 85. Thus it will be seen that it isimpossible to release the cover by pushing the operating handle 41 onlypart of the Way to open circuit position. To release the interlockingmeans to permit opening of the cover 9, it is necessary to move theoperating handle 41 a suiiicient distance in the opening direction tocause the mechanism 2| to effect opening of the contacts of the breaker.

The angularly bent hook end 81 of the clip 85 provides an inclinedcamsurface, and this together with the inherent resiliency of the clip 85allows it to iiex and clear the projection 83 on the operating member 4|when the cover 9 is closed with the operating member 4| in closedcircuit position. This eliminates the possibility of damage to any partsof the circuit breaker in case the cover should be slammed shut when theoperating member 4| is in the on or closed circuit position.

It will be noted that the entire interlocking means comprising thelateral projection 83 and the spring clip 85 is disposed in aninaccessible position entirely within the enclosure 5, where it cannotbe manipulated to eiTect release of the cover when the operating member4| is in closed circuit position.

While the invention has been disclosed in accordance With the provisionsof the patent statutes, it is to be understood that various changes inthe structural details thereof may be made Without departing from thespirit of the invention. It is desired, therefore, that the appendedclaims be given the broadest reasonable interpretation permissible inView of the prior art.

I claim as my invention:

1. In an enclosed electrical switch, an enclosure having an openablecover, an electrical switch mounted within said enclosure having anoperating member operable from outside said enclosure, said cover andsaid operating member being provided one with a projection and the otherwith a spring clip, both of which are disposed within the enclosure, forinterlocking the cover to prevent opening thereof when the switch is inclosed circuit position.

2. In an enclosed circuit breaker, an enclosure having an openablecover, a circuit breaker having an operating mechanism mounted Withinthe enclosure, said operating mechanism being operable from outside saidenclosure, said cover and a movable actuating element of the operatingmechanism being provided one with a projection and the other with aspring clip both of which are disposed within the enclosure forinterlocking the cover to prevent opening thereof when the circuitbreaker is in closed circuit position.

3. In an enclosed circuit breaker, an enclosure having an openablecover, a circuit breaker mounted Within said enclosure having anoperating mechanism including a movable operating member that isoperable from outside said enclosure, interlocking means disposedentirely within said enclosure for interlocking the cover to preventopening thereof when the circuit breaker is in closed circuit positioncomprising a lateral projection carried by said movable operating memberwithin the enclosure and a hook shaped spring clip secured to the insideof the cover in a position such that it is disposed in interlockingrelation relative to the projection on the operating member when theoperating mem.- ber is in and adjacent to its closed position.

Li. In an enclosed circuit breaker, an enclosure having an openablecover, a circuit breaker mounted within said enclosure having anoperating mechanism including a movable operating member that isoperable from outside said enclosure, in combination, interlocking meansfor the cover for preventing opening thereof when the breaker is inclosed circuit position comprising a lateral projection carried by theoperating member within the enclosure, and a spring clip secured to theinside of the cover having a hooked end which underlies the lateralprojection of the operating member when the operating member is in andadjacent its closed circuit position.

5. In an enclosed circuit breaker, an enclosure having an openablecover, a circuit breaker mounted within said enclosure having anovercenter spring operating mechanism including a movable operatingmember that is operable from outside the enclosure, in combination,interlocking means disposed entirely within the enclosure forinterlocking the cover to prevent opening thereof when the circuitbreaker is in closed circuit position comprising a lateral projectioncarried by the operating member within the enclosure and a spring clipsecured to the inside of the cover having a hook end which is disposedin interlocking relation under the lateral projection when the operatingmember is in closed position, said projection and clip being of a widthto prevent opening of the cover during Substantially the full travel ofthe operating member from its closed position to the position at whichthe operating mechanism automatically moves to the open positionindependently of any further movement of the operating member.

6. In an enclosed circuit breaker, an enclosure having an openablecover, a circuit breaker mounted Within said enclosure having anoperating mechanism including a movable operating member that isoperable from outside said enclosure, in combination, interlocking meansfor the cover for preventing opening thereof when the breaker is inclosed circuit position compris- .ing a lateral projection carried bythe operating member within the enclosure, and a spring clip secured tothe inside of the cover having a hooked end which underlies the lateralprojection of the operating member when the operating member is in andadjacent to its closed circuit position, the resiliency of said clippermitting the hooked end thereof to clear said projection duringclosing of the cover when the operating member is in closed position.

THOMAS W. LANGFORD.

